An internal combustion engine, such as, for example, a diesel, gasoline, or natural gas engine, typically includes a cylinder block defining at least one cylinder and one or more of intake and exhaust valves. These valves may be actuated, i.e., selectively opened and closed, to control the amount of intake and exhaust gases that flow to and from the combustion chambers of the engine.
For maximum efficiency, it is generally desirable that the area of the intake and exhaust valves be maximized. To maximize this area, multiple intake valves and multiple exhaust valves are generally associated with each cylinder. In order to ensure that all of the intake valves move simultaneously and to the same lift amount, they are generally opened by a single actuator. The single actuator is connected to each of the intake valves by way of a valve bridge. The single actuator presses on the valve bridge which in turn opens the intake valves at the same time and to the same amount. A similar valve bridge arrangement may be employed for the exhaust valves.
The operational performance of the valve bridge may depend upon the connection between the valves and the valve bridge. The connection between the valves and the valve bridge may provide some clearance to allow for expansion due to heat and/or to allow lubrication between the parts. However, the connection should not be loose to permit the valve bridge to shift in relation to the valves during operation of the engine. In this situation, the valves may open undesirably, resulting in damage to the engine, or the valves may not open at all, resulting in an interruption in engine operation.
Efforts have been made to maintain the connection between the valve bridge and the valves. For example, U.S. Pat. No. 4,327,677 issued to Bok on May 4, 1982 (“the '677 patent”), discloses valves that are connected to the valve bridge through guide pins. Guide apertures extend centrally upward from the crowned contact surfaces of the valve bridge, and each aperture is configured to loosely receive a guide pin. The guide pins extend upwardly from the free end of a valve stem associated with each valve. The inside diameter of the guide apertures is larger than the outside diameter of the guide pins in order to compensate for variations in valve stem height.
Although the valve bridge arrangement of the '677 patent may be somewhat effective in compensating for valve stem height variations, it may be problematic. For example, the difference in diameters between the guide apertures and the guide pins provides a loose connection between the valves and the valve bridge. This loose connection may, in turn, allow the valve bridge to move relative to the valves, and may cause undesirable valve operation.
The device and method of the present disclosure are directed towards improvements in the existing technology.